The Sleep Apnea Syndrome, a recently described condition of disturbed sleep and breathing, is being diagnosed and treated with increasing frequency. Because of this rapidly expanding clinical activity, a more complete description of the Syndrome, better defined diagnostic criteria, and health effect data are needed, especially in patients with less severe versions of this condition. We propose to study the Sleep Apnea Syndrome in a large community-based sample of Hispanic adults. Extensive health data are presently being collected in a large prevalence survey directed at the epidemiology of respiratory disease among Hispanic residents of Belen, New Mexico. This Belen Health Study includes questionnaire items directed at symptoms of Sleep Apnea Syndrome. We propose to use an additional questionnaire, new techniques of home monitoring of breathing during sleep, and polysomnography to define the prevalence of symptoms and objective manifestations of Sleep Apnea Syndrome. The method of subject selection will permit estimates of prevalence rates for the entire adult Hispanic community as well as for subsets classified by sleep symptoms. Associations between symptoms and home monitor data will be used to distinguish normal from affected subjects and to define diagnostic criteria for Sleep Apnea Syndrome. An assessment of the health effect of Sleep Apnea Syndrome will be made by reference to the demographic, socio-economic and health data from the Belen Health Study. The proposed study should provide estimates of Sleep Apnea Syndrome prevalence and health effects that are applicable to the general population. Diagnostic criteria for Sleep Apnea Syndrome and the utility of home monitors for clinical diagnosis will also be determined.